Residential basement flooring system and method using pier capitals for supporting pre-cast slabs

ABSTRACT

A residential flooring system is provided for use with expansive soil. The system includes a plurality of pre-cast slabs of hardened material such as concrete with or without structural members such as rebar and/or wire mesh. The system also includes structural members such as drilled piers, helical screws, caissons, or the like that contact the expansive soil and extend upward away from the expansive soil. The structural members have an upper contact surface that extends above the soil. Weight bearing members are attached to the structural members such as to their upper contact surfaces. Each of the weight bearing members includes a bearing surface that is larger (e.g., has a greater area) than the upper contact surface of the pier or other structural member. The pre-cast slabs are positioned on the weight bearing surfaces so that the slabs are supported by the structural members via the weight bearing members.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/679,758 filed May 11, 2005, which is incorporated herein by referencein its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in general, to the construction ofconcrete slab floors and flooring systems for residential basements,and, more particularly, to a concrete flooring assembly, and method offabrication, for use with expansive soils that utilizes pre-caststructural slabs to create void spaces and provides pier capitals toeffectively support the slabs a distance above the soil.

2. Relevant Background

Residential buildings or houses are often built on foundationscomprising vertical perimeter walls of poured concrete. Since thevertical foundation walls are structural members which support thebuilding, they are usually several feet in depth and function as beamsbridging between footers or piers resting on bedrock or stable soil. Itis common practice in such buildings to provide a basement, or groundfloor, in which at least a portion of the basement walls include thevertical foundation walls and in which the basement floor is a pouredconcrete slab resting on the soil enclosed by the foundation walls.Typically, the foundation is constructed by first excavating a pit forthe basement and for the foundation footers. Then, forms are erectedaround the periphery of the pit and concrete for the foundation walls ispoured into the forms. Next, a form or pan is provided for the flooringslabs and concrete is poured into the floor pans (or, in some cases, thefloor is poured directly onto the soil).

A major problem with conventional construction in certain soil andclimate conditions is that the location of the basement floor can beunstable due to movement of the underlying soil. Expansive soils areprevalent in many areas of the Unites States and other countries. Theseexpansive soils can expand and contract considerably as a result ofcyclical changes in moisture content and/or as a result of freezing andthawing cycles. The soil expansion and contraction problem can beespecially severe when the floor is simply a slab of concrete pouredonto the surface of the soil that forms the floor of the excavation pit.For example, certain dense clay soils tend to dry out after excavationand then later absorb water and swell. This swelling or expansion causesthe slab to move relative to the foundation walls which can generatelarge forces that are sufficient to crack or break the slab. In general,because the foundation walls must support the building, they aresupported by piers or pads on solid ground or bedrock or piers or padson footings and therefore are very stable. However, when the basementfloor is a relatively thin slab of concrete having a large surface areaand resting on a large area of soil, it is highly vulnerable to movementdue to expansion and contraction of the soil as water is absorbed andreleased by the soil. The relative motion between the slab and the wallscan damage interior walls.

A variety of techniques have been implemented to control the effects ofexpansive soils on concrete foundations and structural slabs or floors.Generally, each of these techniques attempts to separate the foundationwalls and structural slabs or flooring from the heaving soils or to atleast absorb some of the expansive forces created by the moving soil.Unfortunately, these techniques have proven to be costly to implement,have increased the complexity of fabricating concrete foundations andflooring, have sometimes caused long-term structural or safety problems,and have reduced spacing between the floor and ceiling.

For example, a common technique of protecting the foundation and slabfrom the expanding soil is to create a void space under the concreteslab. To create the void, cardboard forms or other degradable materialforms are positioned under the form or pan used during pouring of thefoundation walls and floor. With time, the material of the void formbegins to deteriorate creating a void in which the soil can expandwithout moving the wall or floor. However, the degradation of the formstypically is accompanied by mold growth and the release of associatedtoxins, which can result in safety issues within the structure above theconcrete foundation. Additionally, jobsite delays and inclement weatherduring initial construction can result in premature degradation of thecardboard void form and loss of the strength needed to support thecuring concrete wall and floor. Each of these techniques involvescarefully arranging the void forms and pans onsite in the excavated pitand then pouring concrete that makes up the flooring on site, andtypically, the floor is a single, monolithic structure. This onsite workis time consuming and often results in delays due to the time requiredfor finishing and setting of the concrete and due to weather issues.

There remains a need for an improved flooring method and system forcreating structural or flooring slabs and protecting the installed slabsfrom the effects of expansive soils. Preferably, such a method andsystem would be relatively inexpensive to implement in thecost-sensitive construction industry and lend itself to the fieldconditions associated with excavating soil and forming structures withconcrete. Further, the method and system preferably would result in voidspaces being created under structural slabs and control or reduce theuse of degradable void forms that may generate mold or need to beremoved.

SUMMARY OF THE INVENTION

The present invention addresses the above problems by providing aflooring method and system that includes capitals or plinths on top ofpiers to provide a wider or extended weight bearing surface. Pre-cast orpreformed slabs are placed on the capitals and corresponding piers priorto building the foundation walls of the residential structure. The slabsof the invention are typically pre-cast concrete slabs that includesupporting, monolithic ribs or joists of particular width, depth, andspacing for each situation (e.g., for differing load bearingsituations). In some embodiments, a poly foam spacer or insulation isinserted between the ribs prior to casting so as to reduce the overallweight, e.g., to form channels between the ribs, and to thermallyinsulate the floor from nearby soil and air. The pier capitals areincluded in the flooring system to increase the bearing area of a commondrilled pier, caisson, helical screw, or other standard foundationalsupport, and the capitals may be formed in a single pour with a concretepier or later attached to the foundational support. L-shaped bars, e.g.,steel, glass reinforced plastic, or the like may be provided in the slabto provide a mating component and/or lateral support for a wall laterpoured on or formed on the slabs. Also, the slabs typically will includecarrying or edge beams two at opposing ends with the ribs or joistsextending and contacting the edge beams.

More particularly, a residential flooring system is provided for usewith expansive soil. The system includes a plurality of pre-cast slabsof hardened material such as concrete with or without structural memberssuch as rebar and/or wire mesh. The system also includes structuralmembers such as drilled piers, helical screws, caissons, or the likethat contact the expansive soil and extend upward away from theexpansive soil. The structural members have an upper contact surfacethat typically extends above the soil. Weight bearing members or pierextensions are attached to the structural members such as to their uppercontact surfaces. Each of the weight bearing members includes a bearingsurface that is larger (e.g., has a greater area) than the upper contactsurface of the pier or other structural member. The pre-cast slabs arepositioned on or abutting the weight bearing surfaces so that thepre-cast slabs are supported in the system by the structural members viathe weight bearing members.

In typical embodiments, the pre-cast slabs and weight bearing membersare formed of concrete. The weight bearing members generally have sidesthat extend upward and outward from the upper contact surface of thestructural members or piers, e.g., take a frustoconical shape with sidesthat angle at 40 to 80 degrees (as measured from a horizontal planepassing through the upper contact surface to the sides). The pre-castslabs may include a planar member, a pair of edge or carrying beamsextending from the planar member, and two or more monolithic ribsextending in a spaced-apart manner from the planar member between theedge beams. The edge beams of each of the pre-cast slabs typically abutor contact the weight bearing surfaces such that the slabs are supporteda void distance above the expansive soil. In some embodiments, thepre-cast slabs also include insulation positioned between adjacent pairsof the ribs. Further, the system may include a plurality of wallsections positioned upon the pre-cast slabs such that the wall sectionsare supported first by the slabs and then by the weight bearing membersand structural members. In other embodiments, the edge or outer slabsare instead supported by pre-built foundation walls on one end, such aswith an angle iron ledge, dowels, keys, or other support membersextending outward from the foundation wall, and on pier/capitalcombinations on the other end.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a residential floor assembly according to anembodiment of the invention including pre-cast slabs positioned on pierswith weight bearing extensions or capitals;

FIG. 2 is a sectional view taken along line 2-2 in FIG. 1 showing across section of the piers and attached capitals;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1 showing across section of a slab showing carrying or edge beams and a insulatingfoam-filled channel formed between joists or ribs of the slab;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 1 showing joistsor ribs in a slab and the channels formed there between that mayoptionally be filled with insulating foam; and

FIG. 5 illustrates a perspective view with a cutaway section of apre-cast slab of one embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, like reference numerals indicate like features, and areference numeral appearing in more than one figure refers to the sameelement. The drawings and the following detailed descriptions showspecific embodiments of the invention with numerous specific detailsincluding materials, dimensions, and products being provided tofacilitate explanation and understanding of the invention. However, itwill be obvious to one skilled in the art that the present invention maybe practiced without these specific details and these broaderembodiments of the invention are considered within the breadth of thefollowing claims.

In general, the invention is directed to a flooring system that isparticularly well suited for use in residential building. The flooringsystem typically includes a number of structural slabs or assembliesthat are adapted for mounting on piers or drilled piers that aremodified to include a weight bearing extension or capital. The pierswith capitals may be provided in the soil to receive two edge portionsof abutting slabs and in some cases four abutting slabs may be supportedby a capital and its pier (e.g., when four corners of four adjacentslabs meet). The flooring system may include pre-cast wall sections thatare mated with and supported by the slabs or may include a wall that ispoured upon an assembled set of flooring slabs. The mounted pre-castslabs provide void spaces to allow the flooring assemblies to be placedon or in expansive soil. Significantly, these void spaces under thestructural slabs and walls are provided without the use of cardboard,wood, and other degradable materials that may rot, mold, or deterioratein a manner that causes undesirable off-gases or other safety problemsor that may increase the complexity and cost of the flooring assembly orsignificantly reduce the expected life and/or reliability of thefinished structure. The flooring assemblies are discussed in detailbelow with reference to FIGS. 1-5.

One embodiment of a foundation or flooring assembly 100 of the presentinvention is shown in FIG. 1. Prior to the invention, flooring forbuilding such as individual residences were poured on site, whichrequired significant amounts of concrete finishing and fabricationprocesses that can be difficult based on weather. In contrast, theflooring assembly 100 makes use of pre-cast slabs 130 that can aremanufactured offsite, such as at a warehouse or manufacturing facility,are transported to the site, and then lifted and positioned to form afloor. The slabs 130 are typically formed of concrete and may includestructural components such as rebar, mesh or wiring, or the like toincrease their strength. Each slab includes a horizontal or planarmember (e.g., upper surface) in which may be provided a receiving grooveor slot (or other mating components such as dowels when wall pouring isperformed) 133 at an end.

With this in mind, the assembly 100 includes wall sections 150 that inthis embodiment are pre-cast, too. The wall sections 150 are alsotypically formed of concrete and are positioned on the floor 130 to matewith the groove 133 in horizontal member or support surface 132. Tofacilitate mating the wall 150 with the slabs 130, an edge or side 152of the wall 150 is formed to include a protruding ridge or key that isconfigured to fit within the ridge or keyway 133 in the slab 130. Inother embodiments, the wall 150 is poured after placing the floor slabs130 and in these cases, dowels may protrude from the end of the slab 130in place of or in addition to the slot or keyway 133. While not shown,adjacent slabs 130 may also have surfaces adapted for better mating ofslabs 130 such as one having an “L” shape while the other has aninverted or opposite “L” shape to receive the next laid slab 130.

As shown, the structural slabs 130 and wall sections 150 are supportedby piers 110 above the soil or excavation floor 104 to create a voidspace between the slabs 130 and the soil 104, which may expand andcontract. The piers 110 may be poured concrete, helical screws, or thelike, e.g., may be typical drilled piers or caissons as are well-know inthe building industry. Significantly, weight bearing extensions orcapitals 120 are provided on top of the piers 110 so as to bettersupport the slab and wall weight and to eliminate the need fordegradable wood or steel beams and/or void boxes while still providingadequate structural support for the slab during the ongoing use of theslabs 130 in a structure. As shown, the piers 110 typically have atleast a portion that extends outward from the soil 104, and the capitals120 extend from this portion of the pier 110. The capitals or plinths120 provide a receiving or weight bearing surface 126 formed by thesides 122 that angle outward from the pier 110 to provide a largerdiameter, CD. For example, the pier 110 may have a diameter, CD, rangingfrom 8 to 16 inches, such as 10 inches, while the capital surface 126may have a diameter that is significantly larger, such as in the rangeof 18 to 28 inches with diameters in the range of 20 to 24 inches beinguseful in many applications. A circular surface 126 is shown in FIG. 1as this is a relatively easy to form and strong shape, but it will beunderstood that other shapes may be used such as square, rectangular, oranother polygonal perimeter.

As discussed, the slabs 130 are typically formed using concrete that ispoured into a form such as a metal pan (not shown as it would be used atthe offsite manufacturing facility rather than being used on-site andleft as part of the floor structure). The slabs 130 may include channelsformed between joists or ribs and edge or carrying beams as discussedbelow, and for additional strength and integrity, the slabs 130 mayinclude steel bars and/or wire mesh, which may also be used to connectthe structural slabs 130 to the foundation wall 150 in conventionalfashion.

FIG. 2 illustrates a cross sectional view of the floor assembly 100 ofFIG. 1. As shown each slab 130 is formed with channels 238 formed byjoist/rim members and edge or carrying members as discussed below. Inother words, the slabs 130 are not typically solid but instead havechannels 238 but in some cases, the channels 238 are filled withinsulating material or foam to reduce heat transfer from slab 130 tosoil 110 or vice versa. Each slab 130 is supported on top of capitals120, which in turn are supported by piers 110. As shown, two abuttingslabs 130 have end portions 234, 236 that abut or contact each other andare supported by a capital surface 126. For example, each end portion234, 236 may extend to about the center of the capital weight bearingsurface 126. End portions 234, 236 are shown with straight verticalwalls but, as discussed above for edges of the slabs 130, the endportions 234, 236 may include surface configurations to facilitatemating (such as paired/inverted “Ls” or the like). Further, finishingmay be performed to “fill” cracks or spaces between the slabs 130 and/orwalls such as with additional concrete, caulking, or the like.

As shown in FIG. 2, the slab 130 is supported a void distance, VOID,above the soil 104 by the combination of the pier 110, which extends outfrom the soil a distance or pier height, P_(H), and the capital 120,which has a height, C_(H), as measured from the top of or mating surfaceof the pier 110. The pier height, P_(H), is in the range of 0 to 12inches or more with 4 to 8 inches being common but not limiting, and istypically greater than zero to avoid having the soil contacting thesides 122 of the capital 120 upon installation.

The height of the capital, C_(H), also may range significantly topractice the invention and will vary with the diameter of the pier 110and the capital surface 126. This is because the angle, Θm defined bythe sides 122 and a plane extending through the top of the pier 110 isselected to not be too steep or it will make the height, C_(H),unacceptable large to achieve a desired diameter for the capital surface126 and not too shallow as then the capital would not have adequateweight bearing strength. Hence, the capital height, C_(H), typicallywill range from about 4 to 16 inches with 6 to 10 inches being preferred(but, again, not limiting). The side angle, Θ, is also typicallyselected to be steep enough (such as 40 to 80 degrees or the like) toreduce the amount of lift force applied by expanding soil 104. In otherwords, shallow angles for side walls are undesirable as providing asurface for the soil 104 to contact (as opposed to piers 110 which aretypically cylindrical with substantially vertical walls, i.e., thestandard use of only cylindrical piers without protruding edges teachesagainst the use of a weight bearing surface with sides that extendoutward and are not vertical).

The pier 110 is often formed as a drilled pier with a hole being drilledfollowed by a concrete pouring. Rebar or dowel 212 may be provided tofacilitate mating of the later formed capital on the top of the pier110. In other words, the piers 110 are typically formed as an initialstep, and then, the capitals 120 are formed in a second or later pouringof concrete, which bonds to the rebar or dowel 212. In some cases, afunnel or frustoconical form is provided on or contacting the pier 110and concrete is poured into the form. In other embodiments, the capital120 is formed in a single pouring with the pier 110 by providing theform on top of the hole or pier form. In other embodiments (not shown),the capitals 120 are formed with the piers 110 to provide a monolithicor substantially monolithic structural member. For example, a form maybe provided for a single pouring of concrete to produce a pier 110 andthe weight bearing extension or capital 120.

FIG. 3 shows another sectional view of flooring assembly 100. In thisview, the slab 130 is shown supported on pier weight bearing extensionsor capitals 120 to create a desired void between the slab 130 and soil104. Features of the slab 130 are more fully shown including edge orcarrying members 310, 320 on each end of the slab. Typically this is arelatively thick or wide member that is supported on or mates withcapitals 120. For example, the slab may be 6 to 10 inches (and often 8inches) thick, t_(SLAB), and the edge beams 310, 320 may be 10 to 16inches (and, in some cases, about 12 inches) thick or wide as measuredfrom the edge or end of the slab to the channel 238. For added strength,one or more lengths of rebar 312, 322 may be provided extending alongthe length (or a part of the length) of the carrying members or beams310, 320. Between the edge beams 310, 320, the channel 238 is shown tobe filled with insulation 330, e.g., insulating foam or the like, butthis is not required to practice the invention (e.g., see FIG. 5).

In the embodiment 100 of FIG. 3, the horizontal or planar slab member132 is shown to have a thickness, t_(Hor. Member), much less than theslab 130, and in some cases, this thickness is selected from the rangeof 2 to 5 inches, with preferred thicknesses being about 3 inches orsomewhat less (such as 2.7 inches). Often wire mesh will be provided inthe member 132 for added strength and integrity (see, for example, mesh420 in FIG. 4). Also, when the wall 150 is poured on site rather thanpre-cast, rebar or dowels may be provided as shown at 340 to extend inmember 132 and to also extend outward from one of the carrying beams 320to form a connector or mating dowel 342 with wall 150. A groove 133 maystill be provided in the upper surface of member 132 but this is notrequired in this embodiment.

FIG. 4 shows a cross sectional view of the flooring assembly 100 thatshows an end view of two adjacent slabs 130. The slab 130 are shownsupported on capitals 120 and piers 110 (i.e., by resting the carryingmembers (not shown) on the weight bearing surfaces of capitals 120, andin some cases, capitals 120 may be provided to support joists or ribs430 between the two carrying members or beams). As shown, the slabs 130include ribs or joists 430 extending downward from the horizontal orplanar slab member 132 and extend an elongate manner between thecarrying beams or members (not visible in FIG. 4). The ribs or joists430 define open channels 238 between them, which may optionally befilled with insulation 330. For added strength, the joists 430 mayinclude rebar or other structural components 410 while the horizontal orplanar slab member 132 includes mesh or the like 420. The ribs 430 maybe rectangular or square in cross section as shown or may take othershapes such as trapezoidal (e.g., with the sides sloping inward towardeach other such that the ribs 430 are wider near the slab member 132than at the surface near the capitals 120).

The channels 238 have a width, W_(Channel), defined by the opposingfaces of each pair of adjacent joists 430. The joists 430 may have arange of thicknesses or widths to practice the invention such as 3 to 6inches or the like. Similarly, the number and spacing of the joists 430may vary and will typically depend on loading requirements (i.e.,structural goals) and vary with the panel size, which may be 6 to 12feet on a side (rectangular or square) with 8 feet being a useful panellength and width. In these embodiments, the joists may be 24 to 30inches from center to center and this would result in channel widths,W_(Channel), of about 18 to 24 inches or the like (which can be leftopen or filled with insulation 330 as shown).

FIG. 5 illustrates in further detail a slab 130 of the presentinvention. The slab 130 is formed or pre-cast in off-site or at leastnot where it is to be positioned/installed in a building. As shown, theform used for the slab 130 is chosen so as to create a number of joistsor ribs 330 that extend along the length of the slab 130 between edge orcarrying beams such as beam 310. Carrying beam includes rebar 310 asdoes joists 330 as shown at 410. The slab planar or horizontal member132 includes a slot or keyway 133 for receiving a matching member of awall and includes mesh or structural steel/wire 420 for added strengthand integrity.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the present disclosurehas been made only by way of example, and that numerous changes in thecombination and arrangement of parts can be resorted to by those skilledin the art without departing from the spirit and scope of the invention,as hereinafter claimed. For example, some flooring system embodiments ofthe invention involve the use of the pre-cast slabs with foundationwalls that are formed prior to the slabs being positioned. Thesefoundation walls are used to support one end of the slabs (or at leastthe slabs on the periphery of a floor system). Specifically, it will beunderstood that a structural floor is often built after the foundationwall is built. The slabs of the invention may then be doweled to thewall, placed on a ledge (such as one formed of steel angle bolted to thefoundation wall), or other support assembly or components (such asdevices or techniques used to support pans or forms for slabs that arepoured on site rather than pre-cast as called for herein). In theseembodiments, the foundation wall may be supported by standard piers orother structural members or by the piers and capitals of the presentinvention. These outer slabs are supported on the opposite end (and, insome cases, at midpoints via their ribs/joists) by the capitals andpiers of the present invention as shown in the figures. In these cases,the slabs would not include a groove or keyway for receiving a wall butmay include features to facilitate being supported at one end by thefoundation wall, e.g., slots or keyways in the edge or carrying beamsfor receiving or mating with dowels or ledges or the like extendingoutward from the foundation wall. Figures are not provided showingflooring systems with standard foundation walls as these will be readilyunderstood by those skilled in the art and drawings are not required foran understanding of how these may be used to support a slab of theinvention.

1. A residential flooring system for use with in expansive soil,comprising: a plurality of pre-cast slabs of hardened material;structural members contacting the expansive soil and extending upwardaway from the expansive soil, the structural members having an uppercontact surface; and a plurality weight bearing members attached to theupper contact surface, wherein each of the weight bearing memberscomprises a weight bearing surface that is larger than the upper contactsurface and wherein the pre-cast slabs are supported by the structuralmembers by abutting the weight bearing surfaces of the weight bearingmembers.
 2. The flooring system of claim 1, wherein the pre-cast slabsand weight bearing members are formed of concrete.
 3. The flooringsystem of claim 1, wherein the weight bearing members comprise sidesthat extend upward and outward from the upper contact surfaces of thestructural members.
 4. The system of claim 3, wherein the weight bearingmembers are frustoconical in shape and the sides extend upward andoutward from the upper contact surfaces at an angle selected from therange of 40 and 80 degrees.
 5. The system of claim 1, wherein each ofthe pre-cast slabs comprises a planar member, a pair of edge beamsextending from the planar member, and two or more monolithic ribsextending in a spaced-apart manner from the planar member between theedge beams.
 6. The system of claim 5, wherein the edge beams of each ofthe pre-cast slabs abuts the weight bearing surfaces such that thepre-cast slabs are supported above the expansive soil.
 7. The system ofclaim 5, wherein the pre-cast slabs further comprise insulationpositioned between adjacent pairs of the ribs.
 8. The system of claim 1,further comprising a plurality of wall sections positioned upon thepre-cast slabs, whereby the wall sections are supported by the pre-castslabs, the weight bearing members, and the structural members.
 9. Amodular flooring system, comprising: a plurality of concrete slabscomprising a planar member, a pair of edge beams extending from theplanar member, and monolithic ribs extending in a spaced-apart mannerfrom the planar member between the edge beams; piers extending into soiland extending above the soil to expose a circular contact surface havinga diameter; and capitals extending from each of the piers comprising acircular weight bearing surface contacting the edge beams to support theconcrete slabs, wherein a diameter of each of the weight bearing surfaceis greater than the diameter of the circular contact surface.
 10. Thesystem of claim 9, wherein the diameter of the weight bearing surface isgreater than about 20 inches and less than about 24 inches.
 11. Thesystem of claim 9, wherein the capitals and the piers are formed ofconcrete that is provided in separate pourings.
 12. The system of claim9, wherein the capitals are frustoconical in shape.
 13. The system ofclaim 9, where at least some of the capitals support at least two of theconcrete slabs.
 14. The system of claim 9, further comprising a wallpositioned on the concrete slabs on a surface opposite the capitals. 15.The system of claim 9, wherein the concrete slabs further compriseinsulating foam between adjacent pairs of the ribs.
 16. A method ofassembling a modular residential flooring system for use with expansivesoil, comprising: casting a plurality of concrete slabs at a firstlocation; transporting the slabs to a second location; at the secondlocation, providing a plurality of structural members extending into thesoil and extending upward out of the soil to expose a support portion;forming weight bearing members on the support portion of the structuralmembers, wherein each of the weight bearing members comprises a supportsurface with an area greater than the support portion; and positioningthe concrete slabs adjacent each other and in contact with the supportsurfaces of the weight bearing members, wherein the concrete slabs forma substantially planar surface and are supported by the structuralmembers via the weight bearing members.
 17. The method of claim 16,further comprising forming foundation wall sections at a third location,transporting the wall sections to the second location, and positioningthe wall sections in vertical orientation on the concrete slabs.
 18. Themethod of claim 16, wherein the casting of the concrete slabs comprisesproviding a form and filling the form with concrete, the form havinginternal surfaces such that each of the concrete slabs comprises aplanar member, a pair of edge beams extending from the planar member,and monolithic ribs extending in a spaced-apart manner from the planarmember between the edge beams.
 19. The method of claim 18, wherein thecasting further comprises providing in each of the concrete slabsinsulation between adjacent ones of the ribs.
 20. The method of claim16, wherein the providing of structural members comprises spacing thestructural members apart a distance such that at each of the concreteslabs is supported by at least four of the structural members.